There are, both disclosed within the patent art, and available in commerce today, numerous devices for processing poultry gizzards. This aspect of poultry processing, which formerly was a tedious hand procedure, has become increasingly mechanized.
The volume of birds handled by a modern plant, typically hundreds of thousands per day, has magnified the need for efficient machinery. Not only is speed important, it is also necessary to avoid mutilating the gizzards as they are cleaned. Unfortunately, present-day gizzard processors do damage a substantial proportion, often over half, of the gizzards passed through them to the point of commercial unacceptability. In fact, it is sometimes necessary for a producer to purchase gizzards to make up giblet packs for whole birds. A reduced rejection rate would thus be highly desirable.
To process or "harvest" a gizzard, one must by some means: (a) separate the gizzard from the stomach and entrails attached to it, (b) remove stones, sand and other foreign material from the interior of the gizzard, and (c) remove the tough, inedible interior lining. Adequate automated machines exist for performing step (a). These may comprise a pair of counter-rotating parallel rolls separated by a space substantially smaller in width than a gizzard, with helical grooves to advance the gizzards to a portion having teeth that engage the entrails and tear them from the gizzards. Steps (b) and (c) are usually preceded by slitting the gizzard lengthwise in a radial plane, whereupon the gizzard can be spread open for cleaning. The lining, thus exposed, is removed by peeling it from the edible remainder of the organ. Most of the automatic prior art gizzard harvesters have a knife or the like to slit the gizzards as a processing step. This may precede or follow grit removal; in the former case, knife wear is a problem.
An unusual approach is disclosed in U.S. Pat. No. 3,175,244. In that patent, a gizzard is first cleaned by inserting a flushing jet into the gizzard cavity. The gizzard is then telescoped over the free end of a rotating arbor, which in one embodiment has a conical portion with helical, square grooves thereon, that tears the lining from the gizzard without the usual cutting step. This device did not, however, become commercially successful. So, despite the many approaches tried thus far, no device has emerged that is both uncomplicated and capable of harvesting gizzards at high speed with a low rejection rate.
It is therefore an object of this invention to process gizzards in such a way as to minimize their rejection rate. In other words, the object is to remove fully the liner and all grit from each gizzard, without tearing it in half or otherwise making it unmarketable as a giblet.
Indeed, another object is to remove the liner and grit from a gizzard without the customary slitting.
A further object is to perform the steps of cleaning and lining removal at a single station, at essentially the same time.
Another object is to provide the industry with a machine capable of mass-production processing rates while attaining the above objects.